SURFACE OZONE EXPOSURES MEASURED IN FINLAND, 1994, Laurila T. , Lattila H. ,

The occurrence of ozone concentrations and exposure indices related to the adverse effects of ozone upon vegetation are reported for four Finnish background stations. In Finland, ozone concentrations are often near the background tropospheric values of cn. 30 ppb. Very high concentrations are not observed. The maximum 1-h average in this data set was 79 ppb. The exposure parameter, which accumulates growing season 1-h average concentrations above a 40 ppb base-line in daylight hours, gave clearly different exposure sums for the stations. These values varied between 4000 and 8500 ppb-h in the southern archipelago, 3000-6500 ppb-h in the southern coastal region, 2000-4000 ppb-h in central parts of the country, and 400-1000 ppb-h in the northern parts of the country. The date of the start of the vegetative season is important in high northern latitudes, because the spring maximum of ozone concentrations is relatively intense compared to the summer maximum. In northern Scandinavia, ozone exposures are particularly sensitive to the date of the start of the growing season. The long daylight period in northern Scandinavia is less important in this respect, since during the growing season ozone concentrations are usually below 40 ppb during the morning and evening hours. A good correlation was found between growing season average concentrations of the sum of gaseous HNO3 and particulate NO3-, and on ozone exposure index which accumulates concentrations above a 40 ppb base-line, confirming the anthropogenic origin of the elevated ozone exposures

USING GROUND-PENETRATING RADAR TO INVESTIGATE A SUBSURFACE KARST LANDSCAPE IN NORTH-CENTRAL FLORIDA, 1994, Collins Me, Cum M, Hanninen P,

Doline formation in karst areas has been a major concern in Florida. Recently, there has been increased interest in investigating the subsurface conditions that influences preferential flow in these karst landscapes. This information is necessary to improve transport and fate models of contaminants. In addition, there is interest in knowing if the formation and expansion of dolines can be predicted by studying subsurface conditions and flow patterns. The soils on the Newberry Limestone Plain are typically sandy above a thin or absent phosphatic, clayey Hawthorne Formation. Underlying this formation is the Crystal River Limestone. A field survey with ground-penetrating radar (GPR) was conducted on the Newberry Limestone Plain at a site with recently formed dolines. The objectives were (i) to investigate the subsurface materials, (ii) to ascertain subsurface landscape variability, (iii) to relate the subsurface landscapes to subsurface flow patterns, and (iv) to predict doline growth and formation in the study area. The results of this study indicated that the subsurface features; presence of clay over limestone, location of solution pipes and paleo-dolines are variable. In general, the subsurface landscape does not follow the surface topography. Subsurface solute movement can be estimated in these landscapes assuming the clay layer that drapes the limestone acts as an aquatarde. Thus, subsurface modeling of flow at the study site is improved. Locations of paleo-dolines and solution pipes were obvious in the radar data. Predictions, though, of future doline formation and growth at the study site were difficult with GPR. Fracture patterns, e.g. dips in the limestone, can be evaluated and weak zones where paleo-dolines have formed can be identified. This study would not have been possible without the use of the GPR. The radar was able to obtain continuous information on 16% of the site to a depth of 3 m. A highly detailed soil survey using conventional methods would have provided only 0.8% coverage of the site

Pre-Devonian landscape of the Baltic Oil-Shale Basin, NW of the Russian Platform, 1999, Puura Vaino, Vaher Rein, Tuuling Igor,

The erosional relief of Ordovician and Silurian deposits in Estonia was developed during the continental period in late Silurian and early-middle Devonian times. The uplift of the area and marine regression were induced by compressional tectonics in the continental interior related to the closure of the Iapetus and Tornqvist Oceans. In the northern part of the Baltic sedimentary basin (Estonia), on the gentle southerly dipping slope between the Fennoscandian Shield (Finland) and Baltic Syneclise (Latvia), a pre-Devonian, slightly rugged erosional relief with few cuesta was developed. The pre-Devonian erosional landforms -- hills, depressions and escarpments reaching 150 m in height -- were probably buried under the Devonian deposits and then partly re-exposed by pre-Quaternary erosion. These landforms are described in detail using data from several thousands of cores drilled in the course of oil-shale and phosphorite exploration and mining